1. Field of Inventive Concepts
Inventive concepts relate to a semiconductor device and a method of fabricating the same.
2. Related Art
As the feature size of metal oxide semiconductor (MOS) transistors is reduced, the dimensions of the gate and the channel formed under the gate have been reduced accordingly. In order to maintain, or increase, the capacitance between the gate and channel, and thereby improve operating characteristics of the transistor, the thickness of a silicon oxide layer, used primarily as a gate insulating layer, has also been diminished. However, thinner gate insulating layers may dramatically increase leakage currents, leading to higher power consumption and reduced device reliability. High dielectric constant materials (also referred to as high-k materials) have been substituted for silicon oxide in the gate insulating layer, allowing increased gate capacitance (and increased performance) without suffering the consequences of the relatively high leakage currents associated with thin silicon dioxide layers. Additionally, because polysilicon has a relatively high resistance, polysilicon gate electrodes may be replaced by metal gate electrodes to further improve performance.